(Nanowerk Spotlight) Coastal cities, farms, and industries need both fresh water and electricity to function. These essential resources typically require separate, energy-intensive systems to produce – desalination plants to purify seawater and power plants to generate electricity. Engineers have long sought ways to make these processes more efficient, but technical hurdles have persisted. Salt buildup clogs desalination membranes, while attempts to generate power from water movement yield minimal electricity.
Now, researchers at Donghua University have combined these processes in a single, solar-powered device. Their system uses a specially engineered material that simultaneously purifies seawater and generates electrical current, potentially reducing the infrastructure and energy needed to produce these vital resources.
The technology builds on recent advances in materials science, particularly the development of two-dimensional materials like MXene and new understanding of how water molecules interact with nanoscale structures. Previous water purification systems struggled with efficiency and salt accumulation, while water-based electricity generation produced inconsistent power output. This new approach addresses both limitations through an innovative combination of materials and structural design.
The schematic diagram of the system is designed around the AEAS evaporator. AEAS evaporator was constructed using ANF, MXene, and CNTs with a high photothermal effect. The water evaporation generated during desalination by the AEAS evaporator can be harnessed to extract electric. The purified water from the system can be used for wheat irrigation, demonstrating both its non-toxicity and its potential value for agricultural applications. (Image: Reprinted with permission from Wiley-VCH Verlag) (click on image to enlarge)
This aerogel combines three components: aramid nanofibers (the same material used in bulletproof vests), MXene, and carbon nanotubes. These materials form a highly porous structure that enhances water transport and evaporation efficiency.
When sunlight hits the AEAS, its top layer converts light into heat, causing water to evaporate. The material contains molecular structures that attract water, reducing the energy needed for evaporation. This makes the process notably efficient – a single cubic centimeter of the material can purify water at a rate of 2.35 kilograms per square meter every hour.
The aerogel’s layered structure creates an electric effect similar to that found in solar cells, facilitating ion migration and charge separation. As water moves through the material, it separates into positively and negatively charged particles. The different layers naturally attract opposite charges, creating an electric current. A single small unit produces 0.4 volts – about a quarter of the voltage of a AA battery. When researchers connected 15 units together, they generated enough electricity to power LED lights directly.
The water purification performance stands out among similar technologies. The device removes 99.9% of salt ions from seawater, meeting both World Health Organization and U.S. Environmental Protection Agency standards for drinking water. Unlike many desalination systems, it resists salt buildup on its surfaces, maintaining its effectiveness even after a week of continuous operation in concentrated salt solutions.
To demonstrate the practical value of their purified water, the research team used it to irrigate wheat plants. The plants grew normally, reaching 10 centimeters in height within 10 days – matching the growth of plants watered with regular tap water. Plants watered with untreated seawater failed to grow.
The device performed consistently in real-world testing outdoors, maintaining its effectiveness through varying temperatures and humidity levels. Its simple aerogel-based design allows for easy scaling – units can be connected in series to increase voltage or in parallel to increase current output.
This approach offers particular promise for coastal agricultural regions, where fresh water is scarce but seawater and sunlight are abundant. The technology requires no external power source and can produce both irrigation water and electricity from readily available materials. While current power output remains modest, the researchers suggest that larger arrays of these devices could support small-scale agricultural operations with both water and power needs.
The development represents a practical step toward integrating water purification and energy production into a single, solar-powered system. Future research will focus on increasing both water purification rates and electrical output while reducing production costs.
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